Spark-plug.



- A. SCHMIDT.: l SPARK PLUG.

Llcmon FILE 1,135,727. V' A PatentedApr.3,191-5. l

www.. maf/y www..

A TTOH/VEY I UNITED sTATEs PATENT oFFIoE.

ALBEBT SCHMIDT, F FLINT, MICHIGAN, ASSIGNOB TO CHAMPION-IGNITIONCOMPANY, 0l" FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr. 13, 1915.

' Application led May 29, 1914. Serial No. 841,744.

To all 'whom t may concewuyy Be it known that I, ALBERT SCHMIDT, a

citizen of the Republic of France, residing useful Improvements inSpark-Plugs, of

which the following is a specification, reference being had therein tothe accompanying drawings.

In the present state of the art in the manufacture ofy spark plugs, itis usual to incase the insulator member in a metallic bushing which isthreaded for engagement withthe engine cylinder` These elementsaresecured together so as to form a gas-tight seal, but when the plug isin use in an engine cylinder and is subjected to the heat developed bythe internal combustion, it frequently becomes leaky. -This is due tothe fact that the coeiicient of expansion of the metal is much greaterthan thatA of the porcelain or insu-L lator, so that there is aloosening of the joint therebetween. It is one of the objects of thepresent invention to maintain a leak-proof joint between the metal andthe porcelain by initially forming said joint when the metal is heatedto a temperature equal or in excess of any temperature to which it issubsequently subjected.

It is a further object to obtain a simple and expeditious method offorming the joint, and a simple and inexpensive construction of plug ashereinafter set forth.

Inv the drawings: Figure 1 is a longitudinal section through a sparkplug showingl vthe metallic bushing and insulator in engagement, but'before the sealing joint is formed; Fig. 2 is a view lillustrating themethod of'heating the metal and fashioning the same to form the clampingjoint; Fig. 3 isa similar view after the completion of l the joint; andFig. 4 is anvelevation of the completed plug.

A is the metallic bushing provided with the usualthreaded nipple B, andwhich is formed with a main bore and a counter-bore with a shoulder kCtherebetween.

D is a comparatively thin annular flange at the upper end of thecounter-bore.

E is the insulator which has an enlargement F for seating upon theshoulder C within the counter-bore of the plug.y

To secure theinsulator within the sleeve with a gas-proof seal, theseparts'are first Apreferably comparatively on and simultaneously anendw'ise pressure the electrodes. This will reheating the metal ofbushing,

isl applied toi sult, first, in

the most intense heat being in the comparatively thin flange or n D, butthe body portion of the bushing being also heated to a high temperature.The pressure of the die J will then fashion the fin into a bead which ispressed against the.`

gasket H, conforming exactly to the contour of said gasket andconforming the latter exactly to the contour of the insulator so' as-toproduce a gas-tight seal. The plug' thus formed will remain gas-proofregard,

less of the heat to which 1t is subjected in use, for this heat cannever 'equal that to which the metal was subjected when the sealingjoint was formed.

Another advantage resulting from this method of forming the seal is thatthe metal -being in a plastic condition is free fromjresiliency and willmore perfectly conform to the-contour of the porcelain than is possiblewith the cold metal.

What Iclaim as my invention is 1. The method of uniting metallicbushings and insulators of spark plugs, comprising the placingof theinsulator in the bushing, the heating of the metal of the bushing to a-temperature'equal to or in excess o that to which it will besubsequently subjected in use, and the compression of the metal to formthe sealing joint while thus heated. f

2. The method of uniting the metallic bushings and insulators of sparkplugs, com-v prising the heating of the metal and the fashioningfof'-the same while hot into conformity to the insulator to form a gas-tightseal therewith.

3. The method of uniting metallic bushings and insulators of sparkplugs, comprising the heating of the metal to atempera- 4. The method ofuniting metallicbush-Y ings and insulators-of spark pllgs, comprisingthe placing of the insulator in the bushing, placing a compressiblegasket upon said insulator, heating the 4bushing to a temperature atwhich the metal is plastic, and' compressing the metal while hot toconform vthe same to said gasket and the insulator.

- 5. The method of uniting metallic bushings and insulators of sparkplugs, comprising the formation ofthe bushing with a thin ange, theengagement of the insulator with said bushin vthe engagement of thebushing with an e ectric Welder toheat the metal, and the application.of pressure while the metal is hot to conform the thin flange to thecontour of the insulator.

6. The method .of uniting the metallic bushings-with the insulators ofspark plugs, comprising the placing of the vinsulator in initialengagement with the bushing, the engagement of the bushing betweenelectrodes of an electric Welder, one of said electrodes being of dieform, and the a plication of pressure when the metal o .the

bushing is hot to conform the sameto the contourn of the insulator.

7 A spark plug, comprising an insulator and a metallic bushing forciblyconformed bly conformed to and contracted upon said insulator.

9.l A sparkplug, comprising an insulator,

and a metallic bushing having an integral portion thereof hot-fashionedand forcibly contracted upon said insulatorto form a sealing jointtherewith.

10. A spark plug, comprising an insuvlator, having an enlargement, and ametallic bushing provided witha shoulder on ywhich said enlargement isseated and having an integral portion hot-fashioned and forciblylcontracted upon said enlargement to form a sealing joint therewith.

In testimony whereof I aix my signature in presence of two witnesses.

ALBERT SCHMIDT.. Witnesses:

. Loms CHENOLEY, B. O. YINCHARI

